Page 217 - PC2019 Program & Proceedings

PLANT CANADA 2019

P7. Unravelling the aspects of PGPR-mediated modulation of antioxidative defense expression and
secondary metabolic profiling in Solanum lycopersicum under Cd stress
*
Khanna, K. ; P. Ohri; R. Bhardwaj
Guru Nanak Dev University, Amritsar

Plant Growth Promoting Rhizobacteria (PGPR) colonize many plants and have been explored in
rhizosphere for their ability to tolerate toxicities through strengthening antioxidative defense system of
plants and stimulating the production of different secondary metabolites. Although, the role of
Pseudomonas aeruginosa and Burkholdera gladioli in Solanum lycopersicum have not been investigated
yet. Therefore, the present work was conducted to investigate the possible roles of P. aeruginosa and B.
gladioli in mitigation of Cd-induced toxicity in S. lycopersicum. Cd exposure (0.4 mM) led to oxidative
damage, alteration in the antioxidants (enzymatic and non-enzymatic) and secondary metabolites
(phenolic compounds and organic acids). Cd stress resulted in accumulation of oxidative stress markers
(superoxide anion,H2O2,MDA) that were further reduced in PGPR-inoculated seedlings, studied
biochemically and through confocal microscopy. The antioxidants SOD (121%), POD (201%) were
reduced while CAT(65%), GPOX(265%), APOX(126%), GR(95%), GST(124%), glutathione(75%),
ascorbic acid(53%) and tocopherol(245%) were stimulated. However, PGPR exhibited plants further
modulated these antioxidant levels. The secondary metabolites like phenols, flavonoids, anthocyanins,
polyphenols and organic acids (citric, fumaric, succinic, malic) were also enhanced in Cd-treated plants
and their levels were further improved by PGPR inoculation. Gene expression profiling of antioxidant
enzymes (SOD,POD,CAT,APOX,GPOX,GR,GST) and secondary metabolites (CS,FH,SUCLG1,SDH,
MS) was also studied and found to be modulated in PGPR-inoculated seedlings. As a novel aspect,
present study highlighted the role of PGPR in Cd-stress tolerance in S. lycopersicum.

Kanika Khanna (kanika.27590@gmail.com)

P8. Brassica rapa Serine/Arginine-rich protein-like 3 (BrSR-like 3) regulates drought tolerance via
alternative splicing of target genes in a concentration-dependent pathway
Lee, S.; M. Muthusamy; J. Kim; M. Jeong
National Institute of Agricultural Sciences

Plants respond to signals including stresses via transcriptional reprogramming mainly through constitutive
and alternative RNA splicing (AS) events. RNA splicing is a highly ordered and dynamic post-
transcriptional modification catalyzed by numerous non-snRNP proteins including serine/arginine-rich
(SR) proteins along with several other factors. In this study, we attempted to characterize the role of
BrSR45a in drought stress response by comparing the phenotypes, chlorophyll a fluorescence and splicing
pattern of drought-responsive genes of BrSR45a overexpressors, mutant (SALK_052345) along with
control plant (Col-0) in Arabidopsis. No aberrant phenotype was observed in transgenic plants except that
SR45a mutants results in relatively shorter leaf widths. Under drought conditions, the upregulation of
BrSR45a positively correlates the photosynthesis efficiency, drought tolerance and recovery rate upon
rewatering. Further analysis showed that the tolerance efficiency of BrSR45a overexpressors is
concentration dependent. To gain insight into the mode of action of the SR45a proteins implicated in the
drought tolerance mechanism, the AS pattern of 16 genes which includes known drought-responsive and
SR45a interacting genes (U2AF, U4/U5.U6 tri snRNP associated protein (U4/U5.U6)) were investigated
and compared among overexpressors, mutants and controls both under normal and drought conditions.
The splicing pattern of DCP5, RD29A, GOLS1, AKR, U2AF and SDR were different between
overexpressors and mutants under normal conditions. This study reveals that BrSR45a can regulate
drought tolerance via alternative splicing of target genes in a concentration-dependent pathway.

Soo In Lee (silee@korea.kr)

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